In an electronic device such as a semiconductor element, semiconductor parts such as transistors, resistors and the like are arranged on a substrate. Those parts must be electrically isolated from each other, and hence have been two-dimensionally placed apart from each other on the substrate. However, according as the requirement of high-density interconnection, they are nowadays becoming placed three-dimensionally. Specifically, it is getting popular to adopt an electronic device manufacturing process comprising the steps of: placing semiconductor parts two-dimensionally on a substrate; forming a layer of insulating film thereon; and providing other parts on the layer, to produce a multilayer structure.
As a method for forming the above insulating film, there is known a process comprising the steps of: applying a coating composition containing polysilazane, and then curing the formed film to convert the polysilazane into a siliceous film (see, for example, Patent documents 1 to 3).